Fabrication of tungsten oxide-based hybrid photochromic blends by scalable method
Abstract
In this paper we have synthesized tungsten oxide-based organic/inorganic hybrid materials composed of tungsten hexachloride (WCl 6 ) and polyvinylpyrrolidone (PVP) micro- and nanosized fibers. The films are deposited on substrates such as paper, glass, metal, and fabric using techniques including electrospinning, spin coating, fiber drawing, casting, and inkjet printing methods. The films exhibit photochromic properties at room temperature. Distinct from pure WO 3 -based coatings, photochromism of the hybrid films is reversible at ambient conditions without heating or applying an electric field. Photochromic performance of the hybrid films has been studied. From optical properties studies we demonstrate about UV illumination-induced band gap engineering. Mechanism of the photochromic effect in the hybrid films is suggested to be related to defects. We suggest also that illumination with the UV light undergoes by structural point defect formation. The paper introduces a low-cost and scalable synthesis method of tungsten oxide organic/inorganic blends that was deposited on different substrates including paper, glass, metal, and fabric by electrospinning, spin coating, fiber drawing, casting, and inkjet printing. The hybrid films consist of microfibers of the organic/inorganic blend of tungsten hexachloride (WCl 6 ) and polyvinylpyrrolidone (PVP). Microsize and nanosize fibers have been synthesized that enhances durability of the photochromic films and stability with respect to influence of the ultraviolet light.The films exhibit photochromic properties with the contrast of >30 % and transparency in clear state >75 % with durability >5 years. Contrast and speed of light-induced coloration increases whereas the speed of bleaching decreases with increasing the intensity of the ultraviolet component of the sunlight. • Synthesis of hybrid photochromic films composed of microfibers of tungsten hexachloride and polyvinylpyrrolidone. • Deposition of the hybrid photochromic films on paper, glass, metal substrates and on cloth. • Deposition by electrospinning, spin coating, fiber drawing, casting, and inkjet printing methods. • Performance and durability testing. • Contrast >30%, transparency in clear state >75%, durability >5 years.